scx_bpfland: enhance performance consistency and predictability

arighi commented 3 months ago

A set of changes to make performance more consistent and prevent spikes:

scx_bpfland: adjust default time slice to 5ms (default tuning for latency)
scx_bpfland: ensure task time slice never exceeds the slice_ns limit (latency improvement)
scx_bpfland: prevent starvation of regular tasks (prevent interactive tasks from monopolizing the CPUs)
scx_bpfland: unify dispatching kthreads with direct CPU dispatches (dispatch kthreads using per-CPU DSQs instead of SCX_DSQ_LOCAL)
scx_bpfland: drop built-in idle CPU selection logic (drop unused option / cleanup)

Thanks to the CachyOS community that provided an extensive amount of test results and feedback about these changes.

sirlucjan commented 3 months ago

I've been testing it for a few days. Everything works very well.

ptr1337 commented 3 months ago

Also tested by me. Performance seems very good as well as reliability and interactivity.

arighi commented 3 months ago

Removed the unnecessary RCU read lock protection + implemented a better time-based starvation prevention. Tested with the usual gaming + building kernel, everything looks good so far (better than before apparently).

arighi commented 3 months ago

Merging this as it seems pretty stable and well-tested.

sched-ext / scx

scx_bpfland: enhance performance consistency and predictability #410